One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,4)(3,7,8,6)(9,10,13,15)(11,16,12,14)(17,18,21,24)(19,20,23,22)(25,26)(27,30)(28,31)(29,34)(32,38)(33,35)(36,40)(37,39)(1,3)(2,6)(4,7)(5,8)(9,11,13,12)(10,14,15,16)(17,19,21,23)(18,22,24,20)(26,27)(28,35)(32,34)(36,37)(17,20)(18,23)(19,24)(21,22)(25,27,30,26)(28,33,35,31)(29,34,38,32)(36,40,37,39)(1,3)(2,7)(4,6)(5,8)(9,10)(11,14)(12,16)(13,15)(17,20)(18,19)(21,22)(23,24)(25,28,30,35)(26,31,27,33)(29,37,38,36)(32,40,34,39)(1,4,5,2)(3,7,8,6)(9,12,13,11)(10,14,15,16)(17,18)(19,22)(20,23)(21,24)(25,29)(26,32)(27,34)(28,36)(30,38)(31,39)(33,40)(35,37)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.